cellular-infrastructure
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osmo-mgw
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"the big fix", of the E1 subchannel [de]multiplexer. I don't even remember how 

many bugs I fixed during the last couple of hours.  It was never working at
any time before.
This commit is contained in:
Harald Welte 2009-02-18 03:40:58 +00:00
parent f9227c7562
commit 7eb1f621e0
2 changed files with 28 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/openbsc/subchan_demux.h
View File

@ -34,7 +34,8 @@
struct demux_subch {
u_int8_t out_bitbuf[TRAU_FRAME_BITS];
u_int8_t out_idx; /* next bit to be written in out_bitbuf */
u_int16_t out_idx; /* next bit to be written in out_bitbuf */
unsigned int consecutive_zeros;
};
struct subch_demux {

79
src/subchan_demux.c
View File

@ -27,6 +27,7 @@
#include <openbsc/subchan_demux.h>
#include <openbsc/trau_frame.h>
#include <openbsc/debug.h>
static inline void append_bit(struct demux_subch *sch, u_int8_t bit)
{
@ -38,55 +39,25 @@ static const u_int8_t nullbytes[SYNC_HDR_BITS];
/* check if we have just completed the 16 bit zero sync header,
* in accordance with GSM TS 08.60 Chapter 4.8.1 */
static int sync_hdr_complete(struct demux_subch *sch)
static int sync_hdr_complete(struct demux_subch *sch, u_int8_t bit)
{
int rc;
int bits_at_end = 0;
int bits_at_front;
if (sch->out_idx < SYNC_HDR_BITS)
bits_at_end = SYNC_HDR_BITS - sch->out_idx;
bits_at_front = sch->out_idx;
if (bit == 0)
sch->consecutive_zeros++;
else
sch->consecutive_zeros = 0;
if (bits_at_end) {
rc = memcmp(sch->out_bitbuf + sizeof(sch->out_bitbuf) - bits_at_end,
nullbytes, bits_at_end);
if (rc)
return 0;
if (sch->consecutive_zeros >= SYNC_HDR_BITS) {
sch->consecutive_zeros = 0;
return 1;
}
rc = memcmp(sch->out_bitbuf + sch->out_idx, nullbytes,
bits_at_front);
if (rc)
return 0;
return 1;
return 0;
}
/* resynchronize to current location */
static void resync_to_here(struct demux_subch *sch)
{
#if 0
u_int8_t tmp[TRAU_FRAME_BITS];
int sync_hdr_start = sch->out_idx - SYNC_HDR_BITS;
int bytes_at_end;
/* first make copy of old bitbuf */
memcpy(tmp, sch->out_bitbuf, sizeof(tmp));
if (sync_hdr_start < 0)
sync_hdr_start += TRAU_FRAME_BITS;
bytes_at_end = TRAU_FRAME_BITS - sync_hdr_start;
/* copy part after sync_hdr_start */
memcpy(sch->out_bitbuf, tmp + sync_hdr_start, bytes_at_end);
/* copy part before sync_hdr_start */
memcpy(sch->out_bitbuf + bytes_at_end, tmp,
SYNC_HDR_BITS - bytes_at_end);
#else
memset(sch->out_bitbuf, 0, SYNC_HDR_BITS);
#endif
/* set index in a way that we can continue receiving bits after
* the end of the SYNC header */
@ -121,29 +92,32 @@ int subch_demux_in(struct subch_demux *dmx, u_int8_t *data, int len)
for (c = 0; c < NR_SUBCH; c++) {
struct demux_subch *sch = &dmx->subch[c];
u_int8_t inbits;
u_int8_t bit;
/* ignore inactive subchannels */
if (!(dmx->chan_activ & (1 << c)))
continue;
inbits = inbyte >> ((3-c)*2);
/* two bits for each subchannel */
if ((inbyte >> (c * 2)) & 0x01)
if (inbits & 0x01)
bit = 1;
else
bit = 0;
append_bit(sch, bit);
if (sync_hdr_complete(sch))
if (sync_hdr_complete(sch, bit))
resync_to_here(sch);
if ((inbyte >> (c * 2)) & 0x02)
if (inbits & 0x02)
bit = 1;
else
bit = 0;
append_bit(sch, bit);
if (sync_hdr_complete(sch))
if (sync_hdr_complete(sch, bit))
resync_to_here(sch);
/* FIXME: verify the first bit in octet 2, 4, 6, ...
@ -183,7 +157,7 @@ int subch_demux_deactivate(struct subch_demux *dmx, int subch)
static int alloc_add_idle_frame(struct subch_mux *mx, int sch_nr)
{
/* FIXME: allocate and initialize with idle pattern */
/* allocate and initialize with idle pattern */
return subchan_mux_enqueue(mx, sch_nr, trau_idle_frame(),
TRAU_FRAME_BITS);
}
@ -217,7 +191,7 @@ static int get_subch_bits(struct subch_mux *mx, int subch,
num_bits_thistime = num_requested;
/* pull the bits from the txe */
memcpy(bits + num_bits, txe->bits + txe->next_bit, num_requested);
memcpy(bits + num_bits, txe->bits + txe->next_bit, num_bits_thistime);
txe->next_bit += num_bits_thistime;
/* free the tx_queue entry if it is fully consumed */
@ -234,7 +208,7 @@ static int get_subch_bits(struct subch_mux *mx, int subch,
}
/* compact an array of 8 single-bit bytes into one byte of 8 bits */
static u_int8_t compact_bits(u_int8_t *bits)
static u_int8_t compact_bits(const u_int8_t *bits)
{
u_int8_t ret = 0;
int i;
@ -252,13 +226,12 @@ static int mux_output_byte(struct subch_mux *mx, u_int8_t *byte)
int rc;
/* combine two bits of every subchan */
rc = get_subch_bits(mx, 0, &bits[0], 2);
rc = get_subch_bits(mx, 1, &bits[2], 2);
rc = get_subch_bits(mx, 2, &bits[4], 2);
rc = get_subch_bits(mx, 3, &bits[6], 2);
rc = get_subch_bits(mx, 3, &bits[0], 2);
rc = get_subch_bits(mx, 2, &bits[2], 2);
rc = get_subch_bits(mx, 1, &bits[4], 2);
rc = get_subch_bits(mx, 0, &bits[6], 2);
if (!rc)
*byte = compact_bits(bits);
*byte = compact_bits(bits);
return rc;
}